Structure and formation method of semiconductor device with conductive feature

ABSTRACT

A structure and a formation method of a semiconductor device are provided. The method includes forming a conductive feature over a semiconductor substrate and forming a dielectric layer over the conductive feature. The method also includes forming an opening in the dielectric layer to expose the conductive feature. The method further includes forming a conductive material to overfill the opening. In addition, the method includes thinning the conductive material using a chemical mechanical polishing process. A slurry used in the chemical mechanical polishing process includes an iron-containing oxidizer that oxidizes a portion of the conductive material.

PRIORITY CLAIM AND CROSS-REFERENCE

This Application is a division of U.S. patent application Ser. No.16/450,665, filed on Jun. 24, 2019, entitled “Structure and FormationMethod of Semiconductor Device with Conductive Feature,” which claimsthe benefit of U.S. Provisional Application No. 62/712,319, filed onJul. 31, 2018, the entirety of which is incorporated by referenceherein.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. Technological advances in IC materials and design have producedgenerations of ICs. Each generation has smaller and more complexcircuits than the previous generation.

In the course of IC evolution, functional density (i.e., the number ofinterconnected devices per chip area) has generally increased whilegeometric size (i.e., the smallest component (or line) that can becreated using a fabrication process) has decreased. This scaling-downprocess generally provides benefits by increasing production efficiencyand lowering associated costs.

However, these advances have increased the complexity of processing andmanufacturing ICs. Since feature sizes continue to decrease, fabricationprocesses continue to become more difficult to perform. Therefore, it isa challenge to form reliable semiconductor devices at smaller andsmaller sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A-1I are cross-sectional views of various stages of a process forforming a semiconductor device structure, in accordance with someembodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Some embodiments of the disclosure are described. Additional operationscan be provided before, during, and/or after the stages described inthese embodiments. Some of the stages that are described can be replacedor eliminated for different embodiments. Additional features can beadded to the semiconductor device structure. Some of the featuresdescribed below can be replaced or eliminated for different embodiments.Although some embodiments are discussed with operations performed in aparticular order, these operations may be performed in another logicalorder.

FIGS. 1A-1I are cross-sectional views of various stages of a process forforming a semiconductor device structure, in accordance with someembodiments. As shown in FIG. 1A, a semiconductor substrate 100 isreceived or provided. In some embodiments, the semiconductor substrate100 is a bulk semiconductor substrate, such as a semiconductor wafer.For example, the semiconductor substrate 100 includes silicon or otherelementary semiconductor materials such as germanium. In someembodiments, the semiconductor substrate 100 includes an epitaxiallygrown semiconductor layer on a dielectric layer. The epitaxially grownsemiconductor layer may be made of silicon germanium, silicon,germanium, one or more other suitable materials, or a combinationthereof.

In some other embodiments, the semiconductor substrate 100 includes acompound semiconductor. For example, the compound semiconductor includesone or more III-V compound semiconductors having a composition definedby the formula Al_(X1)Ga_(X2)In_(X3)As_(Y1)P_(Y2)N_(Y3)Sb_(Y4), whereX1, X2, X3, Y1, Y2, Y3, and Y4 represent relative proportions. Each ofthem is greater than or equal to zero, and added together they equal 1.The compound semiconductor may include silicon carbide, galliumarsenide, indium arsenide, indium phosphide, one or more other suitablecompound semiconductors, or a combination thereof. Other suitablesubstrate including II-VI compound semiconductors may also be used.

In some embodiments, the semiconductor substrate 100 is an active layerof a semiconductor-on-insulator (SOI) substrate. The SOI substrate maybe fabricated using a separation by implantation of oxygen (SIMOX)process, a wafer bonding process, another applicable method, or acombination thereof. In some other embodiments, the semiconductorsubstrate 100 includes a multi-layered structure. For example, thesemiconductor substrate 100 includes a silicon-germanium layer formed ona bulk silicon layer.

In some embodiments, various device elements are formed in and/or on thesemiconductor substrate 100. Examples of the various device elementsinclude transistors (e.g., metal oxide semiconductor field effecttransistors (MOSFET), complementary metal oxide semiconductor (CMOS)transistors, bipolar junction transistors (BJT), high voltagetransistors, high frequency transistors, p-channel and/or n-channelfield effect transistors (PFETs/NFETs), etc.), diodes, light sensors,one or more other suitable elements, or a combination thereof.

As shown in FIG. 1A, a conductive feature 104 is formed over thesemiconductor substrate 100, in accordance with some embodiments. Insome embodiments, the conductive feature 104 is a conductive contact. Insome embodiments, the conductive feature 104 is electrically connectedto a source/drain structure of a transistor, a gate stack of atransistor, or another element formed below the conductive feature 104.In some embodiments, the conductive feature 104 is made of a metalmaterial. The metal material may include cobalt, ruthenium, gold,platinum, tungsten, one or more other suitable materials, or acombination thereof.

As shown in FIG. 1A, an element 106 is formed over the semiconductorsubstrate 100, in accordance with some embodiments. In some embodiments,the element 106 and the conductive feature 104 are made of differentmaterials. In some embodiments, the element 106 is made of a metalmaterial that is different from the material of the conductive feature104. In some other embodiments, the element 106 is made of asemiconductor material, such as polysilicon.

As shown in FIG. 1A, a dielectric layer 102 is formed over thesemiconductor substrate 100, in accordance with some embodiments. Thedielectric layer 102 surrounds the conductive feature 104 and theelement 106. The dielectric layer 102 may be made of or include siliconoxide, silicon oxynitride, borosilicate glass (BSG), phosphoric silicateglass (PSG), borophosphosilicate glass (BPSG), fluorinated silicateglass (FSG), low-k material, porous dielectric material, one or moreother suitable dielectric materials, or a combination thereof. In someembodiments, one or more dielectric layers and conductive features areformed between the semiconductor substrate 100 and the dielectric layer102.

Afterwards, a dielectric layer 108 is deposited over the dielectriclayer 102, the conductive feature 104, and the element 106, as shown inFIG. 1A in accordance with some embodiments. The material of thedielectric layer 108 may be the same as or similar to those of thedielectric layer 102. The dielectric layer 108 may be deposited using achemical vapor deposition (CVD) process, an atomic layer deposition(ALD) process, a physical vapor deposition (PVD) process, a spin coatingprocess, a spray coating process, one or more other applicableprocesses, or a combination thereof.

In some embodiments, the dielectric layer 108 is then planarized tofacilitate subsequent processes. The dielectric layer 108 may beplanarized using a chemical mechanical polishing (CMP) process, agrinding process, a dry polishing process, an etching process, one ormore other applicable processes, or a combination thereof.

As shown in FIG. 1B, openings 110 and 112 are formed in the dielectriclayer 108, in accordance with some embodiments. The opening 110 exposesthe conductive feature 104. The opening 112 exposes the element 106. Insome embodiments, the opening 110 is substantially as wide as theopening 112. In some other embodiments, the opening 112 is wider thanthe opening 110. The formation of the openings 110 and 112 may involveone or more photolithography processes and one or more etchingprocesses. In some embodiments, the openings 110 and 112 are formedsimultaneously. In some other embodiments, the opening 110 is formedbefore the opening 112.

As shown in FIG. 1C, a conductive material 114 is formed to overfill theopening 110, in accordance with some embodiments. A portion of theconductive material 114 protrudes from the top surface of the dielectriclayer 108. In some embodiments, the conductive material 114 is formeddirectly on the conductive feature 104.

In some embodiments, the conductive material 114 is made of a materialdifferent from that of the conductive feature 104. The conductivematerial 114 may be made of or include tungsten, ruthenium, cobalt,gold, platinum, one or more other suitable materials, or a combinationthereof. In some embodiments, the conductive material 114 is atungsten-containing material. In some other embodiments, the conductivematerial 114 is tungsten. In some other embodiments, the conductivematerial 114 is an alloy containing tungsten.

The conductive material 114 may be formed using a selective growthprocess, a CVD process, an ALD process, an electroless plating process,one or more other applicable processes, or a combination thereof. Insome embodiments, the conductive material 114 is selectively grown orformed on the conductive feature 104 that is made of a specific metalmaterial such as cobalt or ruthenium.

In some embodiments, the conductive material 114 is selectively grown orformed on the conductive feature 104 without being formed in the opening112. For example, the element 106 may be made of a semiconductormaterial. The precursor used for growing or forming the conductivematerial 114 does not react with the element 106 and the dielectriclayer 108. Therefore, no conductive material is formed on the element106 to fill the opening 112. In some embodiments, the precursors used inthe selective growth process include a metal-containing compound and asemiconductor-containing compound. For example, in a particularembodiment the precursors used in the selective growth process includeWF₆ and SiH₄. In some embodiments, the selective growth process isperformed using CVD equipment.

Alternatively, in some other embodiments, a mask element is used tocover the opening 112 during the formation of the conductive material114. Therefore, the conductive material 114 is prevented from beingformed in the opening 112.

Alternatively, in some other embodiments, the opening 112 is formedafter the conductive material 114 is formed to fill the opening 110. Inthese cases, the conductive material 114 is also not formed in theopening 112.

In some embodiments, these is no barrier layer (such as atitanium/titanium nitride layer) formed over sidewalls and a bottom ofthe opening 110 before the conductive material 114 is formed. In someembodiments, the conductive material 114 is in direct contact with thedielectric layer 108. In some embodiments, the adhesion between theconductive material 114 and the dielectric layer 108 is not as strong asthe adhesion between the conductive material 114 and the conductivefeature 104. No barrier layer is formed between the conductive material114 and the dielectric layer 108 to enhance the adhesion therebetween.As a result, one or more holes 116 (or cracks) may be formed between theconductive material 114 and the dielectric layer 108. One of the holes116 may be surrounded by the dielectric layer 108 and the conductivematerial 114. In some cases, the holes 116 are very small. A highresolution transmission electron microscope (HRTEM) or other suitableequipment might be used to observe the holes 116.

In some embodiments, the conductive material 114 and the conductivefeature 104 are in direct contact with each other without beingseparated from each other by a barrier layer. Therefore, electricalresistance between the conductive material 114 and the conductivefeature 104 is significantly reduced since the barrier layer may have ahigh resistance.

As shown in FIG. 1D, a barrier layer 118 is deposited over theconductive material 114, the dielectric layer 108, and the element 106,in accordance with some embodiments. The barrier layer 118 extends onthe sidewalls and bottom of the opening 112. The barrier layer 118 mayfunction as an adhesion layer between the dielectric layer 108 and aconductive material to be formed in the opening 112 later.

In some embodiments, the barrier layer 118 is a single layer. In someother embodiments, the barrier layer 118 has a multilayer structure thatincludes multiple sub-layers. The sub-layers may be made of differentmaterials. The barrier layer 118 may be made of or include titaniumnitride, titanium, tantalum nitride, tantalum, one or more othersuitable materials, or a combination thereof. The barrier layer 118 maybe deposited using a CVD process, a PVD process, an ALD process, one ormore other applicable processes, or a combination thereof.

As shown in FIG. 1E, a conductive material 120 is deposited over thebarrier layer 118, in accordance with some embodiments. The conductivematerial 120 overfills the opening 112. In some embodiments, theconductive material 120 and the conductive material 114 are made of thesame material. In some embodiments, the conductive material 120 is atungsten-containing material. In some other embodiments, the conductivematerial 120 is tungsten. In some other embodiments, the conductivematerial 120 is an alloy containing tungsten. The conductive material120 may be formed using a CVD process.

As shown in FIG. 1F, the conductive material 120, the barrier layer 118,and the conductive material 114 are planarized to expose the dielectriclayer 108, in accordance with some embodiments. In some embodiments, afirst CMP process is used to planarize the conductive material 120, thebarrier layer 118, and the conductive material 114. The dielectric layer108 may function as a CMP stop layer. In some embodiments, the first CMPprocess mentioned above is performed using a first CMP pad. In someembodiments, the first CMP pad is a hard pad.

Afterwards, the structure shown in FIG. 1F is transferred onto a secondCMP pad to perform a second CMP process (or buffing CMP process). Insome embodiments, the second CMP pad is a soft pad that is softer thanthe first CMP pad. The first CMP pad may be used to planarize theconductive material 120 until the dielectric layer 108 is exposed. Thesecond CMP pad may be used to partially remove the conductive materials114 and 120 and the dielectric layer 108 to form conductive featureswith the desired height.

In some embodiments, a first slurry provided onto the first CMP padduring the first CMP process is different from a second slurry providedonto the second CMP pad during the second CMP process (or buffing CMPprocess). In some embodiments, the second slurry includes an oxidizer(or oxidant) that is capable of oxidizing the conductive material 114.The oxidizer may be used to transform a portion of the conductivematerial 114 into an oxide material.

FIG. 1G shows a cross-sectional view of the semiconductor devicestructure after an initial stage of the second CMP process, inaccordance with some embodiments. During an initial stage of the secondCMP process, the oxidizer in the second slurry may oxidize a portion ofthe conductive material 114 and/or a portion of the conductive material120. As a result, a portion of the conductive material 114 is oxidizedand transformed into an oxide material 122A. A portion of the conductivematerial 120 is oxidized and transformed into an oxide material 122B. Insome embodiments, the conductive materials 114 and 120 are made of thesame metal material. In these cases, the oxide materials 122A and 122Bare made of the same metal oxide material.

In some embodiments, the conductive material 114 is made of a metalmaterial. The oxide material 122A is made of an oxide material of themetal material. In some embodiments, the oxide material 122A is made ofa material that is different from that of the dielectric layer 108. Insome embodiments, the conductive material 120 is a tungsten-containingmaterial. In these cases, the oxide material 122A may be made of atungsten-containing oxide material. In some embodiments, the oxidematerial 122A includes tungsten oxide. In some embodiments, the oxidematerial 122A includes WO₃. In some embodiments, the oxide material 122Aincludes or is made of a mixture of WO₃ and WO₂.

In some embodiments, a portion of the second slurry is drawn to reachsidewalls of the hole 116 due to the capillary phenomenon. As a result,a portion of the conductive material 114 that surrounds the hole 116 isoxidized and transformed into the oxide material 122A, as shown in FIG.1G in accordance with some embodiments.

In some embodiments, the portion of the conductive material 114 that isoxidized expands and becomes the oxide material 122A. As a result, thehole 116 is partially filled with the oxide material 122A. In someembodiments, a hole 116′ (that is smaller) is formed between the oxidematerial 122A and the conductive feature 104, as shown in FIG. 1G.Alternatively, the hole 116 may be completely filled with the oxidematerial 122A. The oxide material 122A may prevent the second slurryfrom being further drawn to reach the conductive feature 104. Since thesecond slurry is separated from the conductive feature 104 by the oxidematerial 122A, the conductive feature 104 is prevented from beingnegatively affected by the second slurry.

In some embodiments, the oxidizer in the second slurry includes aniron-containing oxidizer. In some embodiments, the iron-containingoxidizer includes ferric nitrate. In some embodiments, a weightpercentage of the iron-containing oxidizer in the second slurry is in arange from about 0.1% to about 2%. In some other embodiments, theiron-containing oxidizer includes Fe(NO₃)₂, KFe(CN)₆, Fe(NO₃)₃, one ormore other suitable oxidizers, or a combination thereof.

In some embodiments, the second slurry includes an acid and may damagethe conductive feature 104 if the second slurry reaches the conductivefeature 104. For example, the conductive feature 104 may be made ofcobalt or another material having lower resistance to the acid slurry.In some embodiments, the second slurry has a pH value that is in a rangefrom about 2 to about 4.

In some cases, the weight percentage of the iron-containing oxidizer inthe second slurry is smaller than about 0.1%. The amount of theconductive material 114 that is oxidized by the iron-containing oxidizermay be insufficient such that the oxide material 122A may have a smallvolume. As a result, the second slurry might still have chance to reachthe conductive feature 104 during the second CMP process. The secondslurry may therefore damage the conductive feature 104, which leads tolow yield. In some other cases, the weight percentage of theiron-containing oxidizer in the second slurry is greater than about 2%.In these cases, the quality of the conductive material 114 might benegatively affected.

Additionally, utilizing iron-containing oxidizers provides foradditional advantages over other oxidizers. For example, if oxidizerssuch as H₂O₂ are utilized, the oxidizer may not be able to block thehole 116, and the second slurry may reach the conductive feature 104through the hole 116 and damage the conductive feature 104. For example,in embodiments in which the conductive feature 114′ is made of tungsten,the oxide material formed using an oxidizer such as H₂O₂ may be WO₂ thatmay has a relatively small volume and may not be able to block the hole116 and prevent the second slurry from reaching and damaging theconductive feature 104.

In some embodiments, the second slurry further includes an inhibitorthat is used to protect the formed oxide material 122A or 122B. In someembodiments, the inhibitor includes one or more carbon chains. In someembodiments, the carbon number of the carbon chain (or one of the carbonchains) is in a range from 10 to 1000. In some embodiments, a weightpercentage of the inhibitor in the second slurry is in a range fromabout 0.01% to about 1%. In particular embodiments, the inhibitor mayinclude histidine, glycine, polyethylenimine, benzhydryl compounds,benzotriazole, one or more other suitable compounds, or a combinationthereof.

In some embodiments, the second slurry further includes abrasive. Theabrasive may be made of silicon oxide. In some embodiments, a weightpercentage of the abrasive in the second slurry is in a range from about1% to about 4%.

As shown in FIG. 1H, the second CMP process continues to partiallyremove and thin the conductive materials 114 and 120 and the dielectriclayer 108, in accordance with some embodiments. The upper portions ofthe conductive materials 114 and 120, the oxide materials 122A and 122B,and the dielectric layer 108 are removed during the second CMP process.The remaining portions of the oxide materials 122A and 122B formprotective elements 122A′ and 122B′, respectively. In some embodiments,the top surfaces of the protective elements 122A′ and 122B′ aresubstantially coplanar with the top surface of the dielectric layer 108.The remaining portions of the conductive materials 114 and 120 formconductive features 114′ and 120′, respectively.

As shown in FIG. 1H, the protective element 122A′ is positioned betweena portion of the dielectric layer 108 and a portion of the conductivefeature 114′. In some embodiments, the hole 116′ is surrounded by theprotective element 122A′, the conductive feature 114, and the dielectriclayer 108, as shown in FIG. 1H. Due to the protective element 122A′, thesecond slurry is prevented from reaching and damaging the conductivefeature 104.

During the second CMP process, the second slurry is kept at a suitableoperation temperature. In some embodiments, the second slurry is kept ata temperature that is in a range from about 20 degrees C. to about 50degrees C. during the second CMP process.

During the second CMP process, the second slurry is provided onto thesecond CMP pad at a suitable flow rate. The flow rate may be in a rangefrom about 100 mL/min to about 500 mL/min.

During the second CMP process, the second CMP pad is rotated at asuitable rotation speed. The rotation speed may be in a range from about40 RPM to about 120 RPM.

During the second CMP process, a suitable pressure is applied on thesubstrate holder against the second CMP pad. The applied pressure may bein a range from about 50 hPa to about 500 hPa.

As shown in FIG. 1H, the protective element 122A′ has an upper portionthat is positioned above the top surface of the conductive feature 114′.The upper portion has a thickness T. The thickness T may be in a rangefrom about 20 Å to about 50 Å. The protective element 122A′ has a sideportion that is positioned between the sidewall of the conductivefeature 114′ and the dielectric layer 108. The side portion has a widthW. The width W may be in a range from about 5 Å to about 10 Å. Theprotective element 122A′ has a depth D. The depth D may be in a rangefrom about 20 Å to about 50 Å. The conductive feature 114′ has a heightH. The height H may be in a range from about 100 Å to about 300 Å.

As shown in FIG. 1I, a reduction process 130 is used to reduce portionsof the protective elements 122A′ and 122B′ to respectively form metalelements 114″ and 120″, in accordance with some embodiments. In someembodiments, the protective element 122B′ is completely reduced to formthe metal element 120″. In some embodiments, the reduction process 130includes applying a reduction media on the protective elements 122A′ and122B′. In some embodiments, the reduction media is a hydrogen-containingmedia, such as hydrogen gas or hydrogen-containing plasma. In some otherembodiments, a solution or liquid that contains a suitable reducingagent is applied on the protective elements 122A′ and/or 122B′ to formthe metal elements 114″ and 120″.

In some embodiments, the metal elements 114″ and 120″ are electricallyconnected to the conductive features 114′ and 120′, respectively. Afterthe reduction process 130, other conductive features may be formed onthe metal elements 114″ and 120″ to form electrical connections to theconductive features 114′ and 120′, respectively.

In some embodiments, because no barrier layer is formed between theconductive features 114′ and 104, electrical connection between theconductive features 114′ and 104 is significantly improved. In someembodiments, due to the iron-containing oxidizer used in the CMP processfor forming the conductive feature 114′, the protective element 122A′ isformed to prevent the slurry from reaching and damaging the conductivefeature 104. The quality and reliability of the conductive feature 104are therefore ensured.

Many variations and/or modifications can be made to embodiments of thedisclosure. In some other embodiments, the protective element 122A′ hasa profile different from that shown in FIGS. 1H and 1I. Due to differentmaterials used and/or different process conditions applied, the profileof the protective element 122A may be varied. The profiles of theprotective element 122A′ and the conductive feature 114′ may be observedusing a high resolution transmission electron microscope (HRTEM) ordetermined using a secondary ion mass spectrometry (SIMS).

Embodiments of the disclosure involve forming an upper conductivefeature in a dielectric layer by a CMP process. No barrier layer isformed between the upper conductive feature and the dielectric layer.The slurry used in the CMP process includes an iron-containing oxidizer.The iron-containing oxidizer is capable of oxidizing a portion of theupper conductive feature into a protective element made of an oxidematerial. The protective element may prevent the slurry from reachingand damaging a lower conductive feature below the upper conductivefeature. The quality and reliability of the lower conductive feature aretherefore ensured. As mentioned above, no barrier layer is formed. Thereis no barrier layer formed between the lower conductive feature and theupper conductive feature. Electrical connection between the lowerconductive feature and the upper conductive feature is significantlyimproved.

In accordance with some embodiments, a method for forming asemiconductor device structure is provided. The method includes forminga conductive feature over a semiconductor substrate and forming adielectric layer over the conductive feature. The method also includesforming an opening in the dielectric layer to expose the conductivefeature. The method further includes forming a conductive material tooverfill the opening. In addition, the method includes thinning theconductive material using a chemical mechanical polishing process. Aslurry used in the chemical mechanical polishing process includes aniron-containing oxidizer that oxidizes a portion of the conductivematerial.

In accordance with some embodiments, a method for forming asemiconductor device structure is provided. The method includes forminga conductive feature over a semiconductor substrate and forming adielectric layer over the conductive feature. The method also includesforming an opening in the dielectric layer to expose the conductivefeature. The method further includes forming a tungsten-containingmaterial directly on the conductive feature to overfill the opening. Inaddition, the method includes partially removing the tungsten-containingmaterial and the dielectric layer using a chemical mechanical polishingprocess. An iron-containing oxidizer transforms a portion of thetungsten-containing material into an oxide material during the chemicalmechanical polishing process.

In accordance with some embodiments, a semiconductor device structure isprovided. The semiconductor device structure includes a first conductivefeature over a semiconductor substrate and a dielectric layer over thefirst conductive feature. The semiconductor device structure alsoincludes a second conductive feature surrounded by the dielectric layerand electrically connected to the first conductive feature. The secondconductive feature is made of a metal material. The semiconductor devicestructure further includes a protective element between a portion of thesecond conductive feature and a portion of the dielectric layer. Theprotective element is an oxide material of the metal material. Theprotective element has a height that is less than a height of the secondconductive feature.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device comprising: a conductivefeature over a semiconductor substrate; a dielectric layer over theconductive feature; a conductive material located within the dielectriclayer; and an oxidized portion of the conductive material locatedbetween the dielectric layer and a non-oxidized portion of theconductive material, wherein the oxidized portion has a height less thana height of the conductive material.
 2. The semiconductor device ofclaim 1, wherein the conductive material comprises tungsten.
 3. Thesemiconductor device of claim 2, wherein the oxidized portion comprisestungsten oxide.
 4. The semiconductor device of claim 3, wherein thetungsten oxide comprises a mixture of WO₃ and WO₂.
 5. The semiconductordevice of claim 1, further comprising a hole surrounded by the oxidizedportion, the conductive material, and the dielectric layer.
 6. Thesemiconductor device of claim 1, wherein the conductive material and theconductive feature are different materials.
 7. The semiconductor deviceof claim 1, wherein the conductive material is in direct physicalcontact with the dielectric layer.
 8. A semiconductor device comprising:a conductive feature over a semiconductor substrate; a dielectric layerover the conductive feature; a tungsten-containing material directly onthe conductive feature through the dielectric layer; and atungsten-containing oxide located between the tungsten-containingmaterial and the dielectric layer, wherein a portion of thetungsten-containing material is in direct physical contact with thedielectric layer; a second tungsten-containing material extendingthrough the dielectric layer; and a barrier layer fully separating thesecond tungsten-containing material from the dielectric layer.
 9. Thesemiconductor device of claim 8, wherein the tungsten-containingmaterial is tungsten.
 10. The semiconductor device of claim 9, whereinthe tungsten-containing oxide is tungsten oxide.
 11. The semiconductordevice of claim 10, wherein the tungsten oxide comprises a mixture ofWO₃ and WO₂.
 12. The semiconductor device of claim 8, further comprisinga hole surrounded by the tungsten-containing oxide, thetungsten-containing material, and the dielectric layer.
 13. Thesemiconductor device of claim 8, wherein the tungsten-containingmaterial and the conductive feature are different materials.
 14. Thesemiconductor device of claim 8, wherein the tungsten-containing oxidehas a height that is less than a height of the tungsten-containingmaterial.
 15. The semiconductor device of claim 8, wherein the barrierlayer comprises titanium oxide.
 16. A semiconductor device structure,comprising: a first conductive feature over a semiconductor substrate; adielectric layer over the first conductive feature; a second conductivefeature surrounded by the dielectric layer and electrically connected tothe first conductive feature, wherein the second conductive feature ismade of a metal material; and a protective element between a portion ofthe second conductive feature and a portion of the dielectric layer,wherein the protective element is an oxide material of the metalmaterial, wherein the protective element has a height that is less thana height of the second conductive feature.
 17. The semiconductor devicestructure as claimed in claim 16, wherein the metal material comprisestungsten, and the oxide material of the metal material comprisestungsten oxide.
 18. The semiconductor device structure as claimed inclaim 16, wherein the protective element comprises a mixture of WO₃ andWO₂.
 19. The semiconductor device structure as claimed in claim 16,further comprising a hole surrounded by the protective element, thesecond conductive feature, and the dielectric layer.
 20. Thesemiconductor device structure as claimed in claim 16, wherein the firstconductive feature and the second conductive feature are made ofdifferent materials.